<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        
        li {
            list-style-type: none;
        }
        
        .box {
            width: 250px;
            margin: 100px auto;
        }
        
        .box li {
            float: left;
            width: 24px;
            height: 24px;
            background-color: pink;
            margin: 15px;
            background: url(../images/sprite.png) no-repeat;
        }
    </style>
</head>
<body>
    <div class ='box'>
    <ul>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
    </ul>
</div>
<script>
    //1.获取元素  所有的小li
    var lis = document.querySelectorAll('li');
    for(var i =0;i<lis.length;i++){
        //让索引号 乘以 44就是每个li的背景y坐标 index就是y坐标
        var index = i*44;
        lis[i].style.backgroundPosition = '0-'+ index +'px';
    }
</script>
</body>
</html>